Chemical reaction causing I-84 to crumble

In the midst of a larger $375 million facelift, Interstate 84 West is currently dirt and gravel from the New York state line to mile marker 52 between Milford and Matamoras.

BETH BRELJE

In the midst of a larger $375 million facelift, Interstate 84 West is currently dirt and gravel from the New York state line to mile marker 52 between Milford and Matamoras.

This section of the project is costing around $66 million.

Over six years, the Pennsylvania Department of Transportation is completely replacing Interstate 84 in the Pike County area down to the dirt road bed. The replacement will be from the state line to the Route 380 exit, near Greentown. Each section is estimated at $75 million.

This fast-tracked project is needed because a chemical reaction in the cement is causing the road, built between 1972 and 1977, to crumble away.

In the 1960s, the cement industry changed the chemical makeup of cement. This new cement became the industry standard to make concrete.

In the 1980s, PennDOT first noticed I-84 was not holding up as well as it should, and by the early 1990s, scientists understood why: alkali-silica reaction. Some rocks mixed into cement cause a chemical reaction creating a gel inside the concrete. The gel expands with water and cracks the concrete. In time, the concrete crumbles away.

The chemical makeup of rocks in local quarries, which were used for I-84 in Pike County, caused this reaction, PennDOT spokesman James May has explained.

Pothole patching is not enough to hold together the road crumbs. PennDOT predicted that if nothing was done on I-84, it would be a dirt road in 10 years.

A traffic pattern in place since April has I-84 West closed and vehicles moved over to the eastbound lanes, which for now serve as a two-lane highway.

That pattern will be in place until around November when this phase is projected to be done, said Project Manager Carla Medura.

The project includes the replacement of four bridges.

There have been numerous vehicle crashes in and around the construction zone, Medura said.

The most common causes of crashes are aggressive driving from off ramps into the flow of traffic, and many speeders. The posted speed limit is 55 mph, but digital speed display signs often show drivers going between 65 and 75 mph, Medura said.

Philadelphia-based contractor James D. Morrissey is handling the work.